Ms Hillary Woehrle
AAMI
3330 Washington Boulevard, Suite 400
Arlington, Virginia
USA


Dear Ms Woerle,

I received a letter from AAMI regarding review and analysis of 
ISO 10993-12:1996, on November 25, 1996.

First of all, I should like to congratulate its publication.   
I acknowledge with thanks the effort and patience by Don during 
the meetings and revision of the drafts.

We have now two subjects for revision and proposal as follows:

(1) Add new Japanese Reference Materials and their source for supply, 
    and delete old Japanese Control materials and their source in Annex A.

  * p6  Add a citation number 3) at the end of Clause A.2.2.1.
  * p6  Footnote 3) should read:
    Negative-control PEs and positive-control PUs for cytotoxicity and 
    implantation tests are available from Hatano Research Institute, 
    Food and Drug Safety Center, Ochiai 729-5, Hatano-shi, Kanagawa 257, 
    Japan.

  * Add the following to the clause A.2.2.2: "Segmented polyurethane (PU) 
    films containing zinc diethyl- or dibutyldithiocarbmate3).
    
  * p7, Delete "segmented polyurethane films containing zinc diethyl- or 
    dibutyldithiocarbamate12),"  and footnote 12).

(2)  We propose an interlaboratory comparison of the performance of the 
     reference materials for cytotoxicity tests including the Japanese 
     Standard Reference Materials, especially two positive control materials 
     A and B designed for cytotoxicity test as a joint program of WGs 5 and 
     12.  Our design and quality control are described in the paper attached.  
     We can deliver them free of charge.  We believe this program should be 
     useful to compare the sensitivity of test method and reproducibility.



I also enclosed a copy of the letter to Dr. John Lang concerning the business 
of WG14.  Please transfer it to Dr. Marlowe.


Sincerely yours,




Akitada Nakamura, Ph.D.

Encl.